Currently, it is common in both urban and rural areas to depend upon established energy infrastructures, such as electric power and natural gas utilities and the corner gas station, to satisfy the energy needs of the average family. In the final analysis, the major source of energy for these infrastructures is fossil fuel, either as a direct energy source for heat and to power the family automobile, or indirectly as electricity. This reliance upon fossil fuels results in a drain upon fossil fuel resources; additionally, the increasing environmental impacts associated with the consumption of fossil fuels is becoming critical.
Due to the finite limits of fossil fuel reserves and the rapidly increasing U.S. and global demands for energy, alternative energy sources and systems must be developed. In order to be financially and politically viable, such alternatives must be reliable and economical when compared to the currently existing technologies which utilize fossil fuel.
A most readily available source of energy, and one which has been utilized in a very limited way for satisfying certain residential energy requirements of a single-family residence, is solar radiation. Solar radiation has been used for the space heating of a residence by heat transfer to a liquid or "heat storage medium," as illustrated by Thomason, U.S. Pat. No. 3,236,294.
Solar energy has also been converted directly to direct current by various photovoltaic devices, as illustrated by Bell, U.S. Pat. No. 4,002,031. These photovoltaic collector schemes may additionally incorporate some provision for collecting waste heat from the collectors for use in heating needs of the residence.
The various prior art approaches to satisfying certain residential energy needs by utilizing solar radiation as a primary energy source are less than optimum from reliability and economic viewpoints. Extensive backup systems are required for those times when solar radiation is unavailable or insufficient, such as during periods of cloudy weather. In relying upon public utilities for a back-up, the capital expenses would be relatively high; further, such systems would be even less desirable in suburban and rural locations due to the additional expense of extending the public utility service to the residence. The utility's "peak loading" problems also tend to be aggravated by solar homes that depend upon the utility just for backup power.
In considering the energy requirements of the family, it should also be recognized that a majority of families rely upon the automobile as a primary means of transportation. Once again, fossil fuels, specifically petroleum-based liquid fuels, have been utilized as the primary energy source, and the foregoing remarks concerning conservation and pollution apply with ever greater force to the conventional automotive internal combustion gasoline engine.
To avoid the necessity of burning fossil fuels, electric-drive automobiles have been proposed. Such experimental electric automobiles are attracting increasing attention due to the general impression that such a power source will decrease air pollution from unburned hydrocarbons. The basic idea is to charge such automobiles' electrical storage devices from the electric utility during off-peak nighttime hours. The problem with such an approach is that, although one avoids air pollution from the automobile engine, one incurs increasing pollution at the central electric power plant, and additionally, increases the demands upon the utility for more central power plants and more electrical power distribution systems. Further, the public is left with the problem of how to refuel such electric cars during the day if the batteries are drained, as battery charging is usually a lengthy procedure.
In order to solve the problems inherent in an all-electric automobile, experimental hybrid electric automobiles have been developed. These hybrid electric automobiles combine an electric-drive motor with an on-board liquid fossil-fueled engine. Illustrative of such hybrid electric automobiles are the automobiles shown in Berman, U.S. Pat. Nos. 3,566,717 and Toy, 3,525,874. It is noted, however, that these hybrid electric automobiles would, once again, rely either upon the public utilities for electrical power or upon the corner gas station for liquid fuels as their primary sources of energy. Thus, the problems of fossil fuel consumption and the attendant environmental impacts thereof are not resolved but are merely divided between the automobile and the electric utility.